So, I have a personal hypothesis, with no research or studies to back it up whatsoever. This is just me thinking out loud.
If only the foot had something that structurally prevented it from overpronating. From an engineering standpoint, something that was attached to the medial aspect of the foot would serve well to prevent overpronation. The area occupied by the big toe would seem ideal. Something like the big toe, that was able to abduct and splay out, would possibly reduce overpronation. Something similar to the big toe, that wasn't inhibited by shoes from splaying, might work really well!
I saw a nice article in one of Jen's posts.
http://www.thebarefootrunners.org/t...-natural-foot-health-by-my-awesome-lmt.14772/
Myofascial Treatment for Natural Foot Health. By Aaron Gustafson LMT, CAMT II
http://www.transcendbodywork.com/Myofascial_Treatment_for_Natural_Foot_Health.html
"Exercise: Align and Anchor Toe.
Feel the correlation between big toe positioning and pronation.
Have your client stand comfortably, ask them to pronate and supinate their medial arch. Once they’ve found both motions, ask them to supinate, while supinated, abduct their big toe into straight alignment with the first metatarsal ray (see picture). Gently anchor their toe to the ground with fingers from both hands - thumbs on the toenail, first fingers on the sides of the toe, hold their great toe right where it is on the ground- ask them to pronate. Most folks instantly feel the support of aligned bony structure- it’s very difficult to pronate further through this positioning. As the therapist, notice how the force of their body weight is expressed through the end of their toe. When aligned, notice how the weight and force is felt through the tip of their toe and toenail. Experiment with moving them back toward tapered-shoe position, or bunion deformation, feel how the force starts to come through the side of their toe, or their callouses or bunion if present!"